This is an original visual proof that :[br][i]The sum of the 1st n odd numbers is equal to n². [/i][br]1+3+5+...+(2n-1)=n². [br][math]$\sum_{k=1}^n (2k-1) = n^2$[/math][br]

[url=https://www.geogebra.org/m/ddsd97jf][/url][url=https://www.geogebra.org/m/mt8apr5e]https://www.geogebra.org/m/mt8apr5e[/url]